Over the past decade, there has been a significant interest in fluorescence chemical sensing. This has been fueled by advances in instrumentation and light emitting probes such as fluorophores. Fluorophores, also referred to herein as fluorescent molecules, are molecules that absorb electromagnetic radiation and emit light. The wavelength of the emitted light is impacted by many factors, including the structure of the molecule, the presence of bound ions, and solvent properties. Researchers seek to develop fluorophores that undergo measurable changes in their fluorescence in response to conformational changes or ion binding. These molecules may then be used as probes to image, track, and sense such changes.
Fluorophores typically have limitations and drawbacks. For instance, to be useful as indicators or probes, a fluorophore preferably exhibits a combination of, if not all of, a sufficiently high absorption coefficient and quantum yield to absorb radiation from a radiation source and subsequently fluoresce strongly to allow for detection, an emission frequency that can be discriminated from any background autofluorescence, minimal to no photobleaching, and a large Stokes shift to filter out the excitation light. It is also important that fluorophores be low cost and easy to handle for widespread use in standardly-equipped chemical, physical, and cell biology labs, or for use outside of the lab. Because of these requirements, the development of new, useful fluorophores is a difficult task, especially because there is not a good process or set of criteria available to predict a fluorophore's overall properties.